Their detention came as relations between London and Tehran have been cooling over Iran's nuclear ambitions, the war in Iraq and other issues.

But Foreign Secretary Jack Straw said Britain was not drawing wider conclusions about the incident.

Stuart Wise said he and his wife Linda had planned to anchor near the island of Abu Musa, which is claimed by both Iran and the United Arab Emirates, after reading on maps that it was a
safe harbour. Two gunboats pulled up and whisked them to Iran.

"To be frank, we were treated fine. We were treated courteously. We were given food," he told BBC radio from Dubai on Friday.

"At the individual level, I have no complaints about the Iranians we came into contact with."

But he said the couple were questioned for days, without being told what they were accused of.

"I think we had five interrogation teams," he said. "I think they thought this was some subtle form of spying, perhaps."

Alert 

"To be frank, we were treated fine. We were treated courteously"

Stuart Wise,
Freed British national
 

The couple were allowed to phone their family, who alerted the British embassy. They were released on Thursday and flew home overnight, the British Foreign Office said.

"It has been distressing for the Wises and their family," Straw told BBC radio from Baghdad, where he is on a visit. 

"It took a good deal of work behind the scenes to achieve this result and I'm glad we've got there."

But Britain was not drawing wider conclusions.

"I don't think it tells one a huge amount actually," he said.

"You never know with these types of incidents at a local level exactly what has happened which leads to detentions and suspicions."